Crucially, the army with which the US invaded Iraq three years ago was not the one Mr Rumsfeld wished for. If he'd had his way, the original deployment of 250,000 troops in the region would have been far less, were it not for the opposition of military advisers such as General Tommy Franks who pressed for more support on the ground.

Mr Rumsfeld's belief was that by carrying out smaller, surgical strikes, there would be no need to send as many soldiers to topple the Taleban in Afghanistan following 9/11 and former Iraqi president Saddam Hussein three years ago.

Such ideas were consistent with a first term under the administration of President George W. Bush, in which the defence secretary sought to reform the military into something smaller, more dexterous and micro-manageable - much to the chagrin of military top brass.

In many ways the thawing of the cold war and the rise of terrorism justified Mr Rumsfeld's policy; his abject failure to come up with anything like a sufficient plan for post-invasion Iraq, however, is just one of the many reasons behind the mire he now finds himself in.

He has not been helped by the recent claim made by US-based Human Rights Watch that Mr Rumsfeld could be 'criminally liable' for what it described as the torture of a detainee at Guantanamo Bay.

His failure to endear himself to certain military figures who believe that the defence secretary's policies helped create the Abu Ghraib abuse scandal by placing too much responsibility on under-trained troops has also cost him dearly.

'We need leadership up there that respects the military, as they expect the military to respect them. And that leadership needs to understand teamwork,' said retired major-general John Batiste, who commanded the 1st Infantry Division in Iraq between 2004 and 2005. Refusing a promotion to three-star rank and passing up the opportunity to become the No2 US military officer in Iraq due to his unwillingness to serve under Mr Rumsfeld, Mr Batiste's assertion is all the more significant in the light of his former role: aide to former Pentagon chief Paul Wolfowitz, another architect of the conflict.

Or there's Paul Eaton, a former American general in charge of training Iraqi forces until 2004, who said Mr Rumsfeld had 'shown himself incompetent strategically, operationally and tactically', and was 'far more than anyone else, responsible for what has happened to our important mission in Iraq'.

They blame foggy intelligence used to justify the war and Mr Rumsfeld's micromanagement as crucial factors preventing US forces from having adequate resources to do the job. Yet Mr Rumsfeld's belief that the US could achieve the maximum result with the minimum of resources also holds a mirror up to his contradictory nature.

His assertion that fewer troops were needed for an Iraq invasion signified a conviction that victory would be both swift and forthcoming. This in turn begs the question: if the administration really knew that Hussein held weapons of mass destruction, what would have been so easy about defeating him? For anyone arguing that the US knew there were no such weapons, such a contradiction makes compelling evidence.

As it stands, the failure to secure an Iraq where there are up to 75 attacks daily - according to figures from the Washington-based Brookings Institution - shows a lack of preparedness for any outcome.

For his detractors, such inconsistencies are at the heart of the matter. 'We are paying the price for the lack of credible planning, or the lack of a plan,' said General Anthony Zinni of the United States Marine Corps, formerly head of United States Central Command.

'Ten years' worth of planning were thrown away, plans that had taken into account what we would face in an occupation of Iraq.'

All of this of course supports Mr Rumsfeld's well-publicised reputation for being aggressive, arrogant, vindictive and unwilling to discern criticism from disloyalty.

The most pivotal secretary of defence since Robert McNamara in the Vietnam era - who was another civilian leader whose penchant for micro-management infuriated his military counterparts - Mr Rumsfeld has also been one of the Bush administration's most demonised figures.

And as the former All-Navy Wrestling Champion has recently shown in his own spiky self-defence, he is only too happy to have these kind of arguments.

This is, after all, the man who once wrote: 'If you are not criticised, you are not doing your job.'

Take, for example, his justification as to why he should stay on in the job: 'Out of thousands and thousands of admirals and generals, if every time two or three people disagreed we changed the secretary of defence of the United States, it would be like a merry-go-round,' he told Arabic TV channel al-Arabiya.

Elsewhere he stated that the nation's 6,000 or 7,000 retired generals and admirals were not 'unanimous on anything'.

He's similarly unafraid to take on his own peers, as shown by his withering response to Secretary of State Condoleezza Rice's admission that the US had committed thousands of 'tactical errors' in Iraq.

'If someone says well, that's a tactical mistake,' said Mr Rumsfeld, 'then I guess it's a lack of understanding... of what warfare is about.'

The question now is whether Mr Bush, faced with his lowest approval ratings of 36 per cent, will bow to growing pressure to sack the architect of his military movements. It's highly unlikely that he will.

'I'm the decider, and I decide what's best' was the president's eloquent response.

Yet Mr Bush's definition of 'what's best' surely includes not admitting defeat in Iraq, which sacking Mr Rumsfeld would of course be tantamount to.

Three years on from his unabashed 'Mission Accomplished' cakewalk on the deck of the USS Abraham Lincoln announcing the 'end' of the military strike, for the president to get rid of Mr Rumsfeld now would be to undo any last vestige of success that the administration is desperately trying to project.

Yet pressure will grow in coming months, especially if Republicans running in the November election decide that the continued presence of 'Rummy' in the cabinet could become a liability. A sense of caution has been generated by the fact that the controversies surrounding Mr Rumsfeld are building at a time when success in Iraq is clearly fading, threatening to make him something of a political albatross come election time.

With congressmen back from a two-week break next week, indications as to whether Senate Republicans might be seeking another change to add to the recent White House reshuffle will become clearer.

Of course, the same was said in 2004, ahead of the presidential election. Back then, many argued that Mr Bush ought to have accepted Mr Rumsfeld's offer to resign when the scandals of Abu Ghraib and Guantanamo Bay were first revealed.

Of course Mr Bush only reiterated his praise for his defence secretary, despite the fact that in the same month as that infamous 'army' comment it was also revealed that Mr Rumsfeld had used a machine to sign condolence letters to the families of soldiers killed in Iraq and Afghanistan, rather than signing the letters personally.

Even before 9/11, Mr Rumsfeld was considered the weakest link, and the resignation of the former health-care chief seemed an inevitability before the stories emerged of him heroically rushing out of his office to tend to survivors after the Pentagon attack. Sentiment shifted and the president even jokingly referred to him as 'Rumstud'.

At 73, he's the oldest person to have held the position; he was also the youngest to do so when he served as the 13th secretary of defence from 1975 to 1977 under president Gerald Ford.

Experience is what Mr Bush brought him in for; and his current reluctance to make his friend walk the plank is of course a face-saving exercise for the both of them, in light of a US$500 billion war in which more than 2,300 Americans and thousands more Iraqis have died.

The next few weeks, however, will be crucial in determining exactly how expensive keeping Mr Rumsfeld on board will really be.